Yes, this has changed with the spelling reform: according to canoo, it was laufenden before and Laufenden after the reform. Quite generally, capitalization has been simplified with the spelling reform – as a rule of thumb, you use a capital letter whenever the word is nominalized. Here the article dem shows us that it is auf dem Laufenden.

The old spelling was more complicated, but it allowed subtle differences: adjectives were often not capitalized when used in the figurative sense. So before the reform it was